Generally, a load cell comprises a flexure member to which the force being measured is applied. The flexure member flexes by an amount proportional to the magnitude of the applied force. Strain gauges of the type that change their electrical resistance in response to distortion are coupled to the flexure member for generating an electrical signal in accordance with the force being measured. In some such load cells, the strain gauges are attached directly to the surface of the flexure members. For example, see U.S. Pat. No. 4,747,456 issued May 31, 1988 to Kitagawa et al.
One of the problems generally encountered with the strain gauges applied to such load cells is that of creep, whereby the output signal slowly changes over time when the gauge is stressed and held in the stressed position. Another problem often encountered is that of hysteresis, whereby the signal does not return to zero when the stress is removed from the load cell, the load cell must be stressed in the opposite direction to force the output to return to zero. Another problem often encountered is that of temperature sensitivity. That is, the output of the gauges on the load cell change with changes in temperature, resulting in the need for complex temperature compensating mechanisms to be built into the strain gauges (see U.S. Pat. No. 4,747,456 above).